This disclosure relates generally to electronic circuits, and in particular but not exclusively, relates to electronic circuits used in differential bi-directional signaling.
A typical integrated circuit (chip) includes input circuits to receive signals from other parts of the chip or from circuitry external to the chip (e.g., via the pins of the chip). The input circuits output the received signals with xe2x80x9crestoredxe2x80x9d voltage levels and appropriate driving current to other parts of the chip. As is well known, a variety of sources may inject noise into the signal received by the input circuit. For example, sources include ringing caused by mismatched output drivers or interconnect impedance, signal cross coupling, and power supply noise. These sources can cause common mode noise that can cause an input circuit to improperly output the received signal.
One conventional solution to this common mode noise problem is to use differential signals. However, the conductive lines used to propagate the signals occupy valuable area in the chip. In addition, chips typically have a limited number of pins available for receiving external signals. These problems apply to single-ended signals as well, but are exacerbated when differential signals are used because of the dual lines needed for each differential signal.